S5151 From Gut to Systemic: IgE and Hypereosinophilia in H. pylori Infection

Introduction: Helicobacter pylori affects nearly half of the global population and remains a significant public health concern. Increasing evidence suggests a complex interplay between H. pylori infection and the host immune response, particularly involving eosinophilia and elevated immunoglobulin E (IgE). This is a case of a 54-year-old woman who presented with gastrointestinal symptoms and was incidentally found to have marked peripheral eosinophilia and elevated serum IgE, all of which resolved following successful H. pylori eradication. Case Description/Methods: A 54-year-old woman presented with acute onset abdominal pain and diarrhea, initially concerning for viral gastroenteritis. Incidentally, a new peripheral eosinophilia was found (absolute eosinophil count: 4,150/μL). This prompted a comprehensive hypereosinophilia work-up including serum IgE, H. pylori stool antigen, parasitic testing, urine eosinophils, endoscopy, and referrals to General Surgery and Oncology. Stool testing was positive for H. pylori, and repeat testing confirmed eosinophilia and elevated IgE (771 IU/mL). The patient was started on standard 14-day triple therapy with amoxicillin, clarithromycin, and pantoprazole. Oncology evaluation ruled out hematologic malignancy with normal peripheral smear, BCR-ABL FISH, JAK2, serum protein electrophoresis with immunofixation (SPEP/IFE), serum free light chains (kappa/lambda), and flow cytometry. A follow-up esophagogastroduodenoscopy 1 month post-treatment confirmed histologic eradication of H. pylori, revealing only mild chronic gastritis. Gradually, the patient's gastrointestinal symptoms resolved, and subsequent testing showed normalization of the eosinophil count and IgE levels. Discussion: This case highlights the association between H. pylori infection and peripheral eosinophilia and elevated serum IgE, both of which resolved following eradication therapy. While H. pylori is a well established cause of gastrointestinal conditions, its potential role in modulating systemic immune responses, particularly involving eosinophils and IgE remains an area of emerging interest. H. pylori has a complex role in the immune system, potentially triggering eosinophilic responses while also modulating allergic diseases. Further research is warranted to define when H. pylori acts as a pro-inflammatory versus protective agent, factoring in strain differences, host genetics, and environmental influences.